/*
** $Id: ldo.c,v 2.108 2012/10/01 14:05:04 roberto Exp $
** Stack and Call structure of Lua
** See Copyright Notice in lua.h
*/


#include <setjmp.h>
#include <stdlib.h>
#include <string.h>

#define ldo_c
#define LUA_CORE

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lundump.h"
#include "lvm.h"
#include "lzio.h"




/*
** {======================================================
** Error-recovery functions
** =======================================================
*/

/*
** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
** default, Lua handles errors with exceptions when compiling as
** C++ code, with _longjmp/_setjmp when asked to use them, and with
** longjmp/setjmp otherwise.
*/
#if !defined(LUAI_THROW)

#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
/* C++ exceptions */
#define LUAI_THROW(L,c) throw(c)
#define LUAI_TRY(L,c,a) \
    try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
#define luai_jmpbuf int  /* dummy variable */

#elif defined(LUA_USE_ULONGJMP)
/* in Unix, try _longjmp/_setjmp (more efficient) */
#define LUAI_THROW(L,c) _longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a }
#define luai_jmpbuf jmp_buf

#else
/* default handling with long jumps */
#define LUAI_THROW(L,c) longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
#define luai_jmpbuf jmp_buf

#endif

#endif



/* chain list of long jump buffers */
struct lua_longjmp {
    struct lua_longjmp *previous;
    luai_jmpbuf b;
    volatile int status;  /* error code */
};


static void seterrorobj(lua_State *L, int errcode, StkId oldtop) {
    switch (errcode) {
        case LUA_ERRMEM: {  /* memory error? */
            setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
            break;
        }
        case LUA_ERRERR: {
            setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
            break;
        }
        default: {
            setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
            break;
        }
    }
    L->top = oldtop + 1;
}


l_noret luaD_throw(lua_State *L, int errcode) {
    if (L->errorJmp) {  /* thread has an error handler? */
        L->errorJmp->status = errcode;  /* set status */
        LUAI_THROW(L, L->errorJmp);  /* jump to it */
    } else { /* thread has no error handler */
        L->status = cast_byte(errcode);  /* mark it as dead */
        if (G(L)->mainthread->errorJmp) {  /* main thread has a handler? */
            setobjs2s(L, G(L)->mainthread->top++, L->top - 1);  /* copy error obj. */
            luaD_throw(G(L)->mainthread, errcode);  /* re-throw in main thread */
        } else { /* no handler at all; abort */
            if (G(L)->panic) {  /* panic function? */
                lua_unlock(L);
                G(L)->panic(L);  /* call it (last chance to jump out) */
            }
            abort();
        }
    }
}


int luaD_rawrunprotected(lua_State *L, Pfunc f, void *ud) {
    unsigned short oldnCcalls = L->nCcalls;
    struct lua_longjmp lj;
    lj.status = LUA_OK;
    lj.previous = L->errorJmp;  /* chain new error handler */
    L->errorJmp = &lj;
    LUAI_TRY(L, &lj,
             (*f)(L, ud);
            );
    L->errorJmp = lj.previous;  /* restore old error handler */
    L->nCcalls = oldnCcalls;
    return lj.status;
}

/* }====================================================== */


static void correctstack(lua_State *L, TValue *oldstack) {
    CallInfo *ci;
    GCObject *up;
    L->top = (L->top - oldstack) + L->stack;
    for (up = L->openupval; up != NULL; up = up->gch.next)
        gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
    for (ci = L->ci; ci != NULL; ci = ci->previous) {
        ci->top = (ci->top - oldstack) + L->stack;
        ci->func = (ci->func - oldstack) + L->stack;
        if (isLua(ci))
            ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
    }
}


/* some space for error handling */
#define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)


void luaD_reallocstack(lua_State *L, int newsize) {
    TValue *oldstack = L->stack;
    int lim = L->stacksize;
    lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
    lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
    luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
    for (; lim < newsize; lim++)
        setnilvalue(L->stack + lim); /* erase new segment */
    L->stacksize = newsize;
    L->stack_last = L->stack + newsize - EXTRA_STACK;
    correctstack(L, oldstack);
}


void luaD_growstack(lua_State *L, int n) {
    int size = L->stacksize;
    if (size > LUAI_MAXSTACK)  /* error after extra size? */
        luaD_throw(L, LUA_ERRERR);
    else {
        int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
        int newsize = 2 * size;
        if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
        if (newsize < needed) newsize = needed;
        if (newsize > LUAI_MAXSTACK) {  /* stack overflow? */
            luaD_reallocstack(L, ERRORSTACKSIZE);
            luaG_runerror(L, "stack overflow");
        } else
            luaD_reallocstack(L, newsize);
    }
}


static int stackinuse(lua_State *L) {
    CallInfo *ci;
    StkId lim = L->top;
    for (ci = L->ci; ci != NULL; ci = ci->previous) {
        lua_assert(ci->top <= L->stack_last);
        if (lim < ci->top) lim = ci->top;
    }
    return cast_int(lim - L->stack) + 1;  /* part of stack in use */
}


void luaD_shrinkstack(lua_State *L) {
    int inuse = stackinuse(L);
    int goodsize = inuse + (inuse / 8) + 2 * EXTRA_STACK;
    if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
    if (inuse > LUAI_MAXSTACK ||  /* handling stack overflow? */
            goodsize >= L->stacksize)  /* would grow instead of shrink? */
        condmovestack(L);  /* don't change stack (change only for debugging) */
    else
        luaD_reallocstack(L, goodsize);  /* shrink it */
}


void luaD_hook(lua_State *L, int event, int line) {
    lua_Hook hook = L->hook;
    if (hook && L->allowhook) {
        CallInfo *ci = L->ci;
        ptrdiff_t top = savestack(L, L->top);
        ptrdiff_t ci_top = savestack(L, ci->top);
        lua_Debug ar;
        ar.event = event;
        ar.currentline = line;
        ar.i_ci = ci;
        luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
        ci->top = L->top + LUA_MINSTACK;
        lua_assert(ci->top <= L->stack_last);
        L->allowhook = 0;  /* cannot call hooks inside a hook */
        ci->callstatus |= CIST_HOOKED;
        lua_unlock(L);
        (*hook)(L, &ar);
        lua_lock(L);
        lua_assert(!L->allowhook);
        L->allowhook = 1;
        ci->top = restorestack(L, ci_top);
        L->top = restorestack(L, top);
        ci->callstatus &= ~CIST_HOOKED;
    }
}


static void callhook(lua_State *L, CallInfo *ci) {
    int hook = LUA_HOOKCALL;
    ci->u.l.savedpc++;  /* hooks assume 'pc' is already incremented */
    if (isLua(ci->previous) &&
            GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
        ci->callstatus |= CIST_TAIL;
        hook = LUA_HOOKTAILCALL;
    }
    luaD_hook(L, hook, -1);
    ci->u.l.savedpc--;  /* correct 'pc' */
}


static StkId adjust_varargs(lua_State *L, Proto *p, int actual) {
    int i;
    int nfixargs = p->numparams;
    StkId base, fixed;
    lua_assert(actual >= nfixargs);
    /* move fixed parameters to final position */
    fixed = L->top - actual;  /* first fixed argument */
    base = L->top;  /* final position of first argument */
    for (i = 0; i < nfixargs; i++) {
        setobjs2s(L, L->top++, fixed + i);
        setnilvalue(fixed + i);
    }
    return base;
}


static StkId tryfuncTM(lua_State *L, StkId func) {
    const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
    StkId p;
    ptrdiff_t funcr = savestack(L, func);
    if (!ttisfunction(tm))
        luaG_typeerror(L, func, "call");
    /* Open a hole inside the stack at `func' */
    for (p = L->top; p > func; p--) setobjs2s(L, p, p - 1);
    incr_top(L);
    func = restorestack(L, funcr);  /* previous call may change stack */
    setobj2s(L, func, tm);  /* tag method is the new function to be called */
    return func;
}



#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))


/*
** returns true if function has been executed (C function)
*/
int luaD_precall(lua_State *L, StkId func, int nresults) {
    lua_CFunction f;
    CallInfo *ci;
    int n;  /* number of arguments (Lua) or returns (C) */
    ptrdiff_t funcr = savestack(L, func);
    switch (ttype(func)) {
        case LUA_TLCF:  /* light C function */
            f = fvalue(func);
            goto Cfunc;
        case LUA_TCCL: {  /* C closure */
            f = clCvalue(func)->f;
Cfunc:
            luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
            ci = next_ci(L);  /* now 'enter' new function */
            ci->nresults = nresults;
            ci->func = restorestack(L, funcr);
            ci->top = L->top + LUA_MINSTACK;
            lua_assert(ci->top <= L->stack_last);
            ci->callstatus = 0;
            luaC_checkGC(L);  /* stack grow uses memory */
            if (L->hookmask & LUA_MASKCALL)
                luaD_hook(L, LUA_HOOKCALL, -1);
            lua_unlock(L);
            n = (*f)(L);  /* do the actual call */
            lua_lock(L);
            api_checknelems(L, n);
            luaD_poscall(L, L->top - n);
            return 1;
        }
        case LUA_TLCL: {  /* Lua function: prepare its call */
            StkId base;
            Proto *p = clLvalue(func)->p;
            luaD_checkstack(L, p->maxstacksize);
            func = restorestack(L, funcr);
            n = cast_int(L->top - func) - 1;  /* number of real arguments */
            for (; n < p->numparams; n++)
                setnilvalue(L->top++);  /* complete missing arguments */
            base = (!p->is_vararg) ? func + 1 : adjust_varargs(L, p, n);
            ci = next_ci(L);  /* now 'enter' new function */
            ci->nresults = nresults;
            ci->func = func;
            ci->u.l.base = base;
            ci->top = base + p->maxstacksize;
            lua_assert(ci->top <= L->stack_last);
            ci->u.l.savedpc = p->code;  /* starting point */
            ci->callstatus = CIST_LUA;
            L->top = ci->top;
            luaC_checkGC(L);  /* stack grow uses memory */
            if (L->hookmask & LUA_MASKCALL)
                callhook(L, ci);
            return 0;
        }
        default: {  /* not a function */
            func = tryfuncTM(L, func);  /* retry with 'function' tag method */
            return luaD_precall(L, func, nresults);  /* now it must be a function */
        }
    }
}


int luaD_poscall(lua_State *L, StkId firstResult) {
    StkId res;
    int wanted, i;
    CallInfo *ci = L->ci;
    if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
        if (L->hookmask & LUA_MASKRET) {
            ptrdiff_t fr = savestack(L, firstResult);  /* hook may change stack */
            luaD_hook(L, LUA_HOOKRET, -1);
            firstResult = restorestack(L, fr);
        }
        L->oldpc = ci->previous->u.l.savedpc;  /* 'oldpc' for caller function */
    }
    res = ci->func;  /* res == final position of 1st result */
    wanted = ci->nresults;
    L->ci = ci = ci->previous;  /* back to caller */
    /* move results to correct place */
    for (i = wanted; i != 0 && firstResult < L->top; i--)
        setobjs2s(L, res++, firstResult++);
    while (i-- > 0)
        setnilvalue(res++);
    L->top = res;
    return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
}


/*
** Call a function (C or Lua). The function to be called is at *func.
** The arguments are on the stack, right after the function.
** When returns, all the results are on the stack, starting at the original
** function position.
*/
void luaD_call(lua_State *L, StkId func, int nResults, int allowyield) {
    if (++L->nCcalls >= LUAI_MAXCCALLS) {
        if (L->nCcalls == LUAI_MAXCCALLS)
            luaG_runerror(L, "C stack overflow");
        else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS >> 3)))
            luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
    }
    if (!allowyield) L->nny++;
    if (!luaD_precall(L, func, nResults))  /* is a Lua function? */
        luaV_execute(L);  /* call it */
    if (!allowyield) L->nny--;
    L->nCcalls--;
}


static void finishCcall(lua_State *L) {
    CallInfo *ci = L->ci;
    int n;
    lua_assert(ci->u.c.k != NULL);  /* must have a continuation */
    lua_assert(L->nny == 0);
    if (ci->callstatus & CIST_YPCALL) {  /* was inside a pcall? */
        ci->callstatus &= ~CIST_YPCALL;  /* finish 'lua_pcall' */
        L->errfunc = ci->u.c.old_errfunc;
    }
    /* finish 'lua_callk'/'lua_pcall' */
    adjustresults(L, ci->nresults);
    /* call continuation function */
    if (!(ci->callstatus & CIST_STAT))  /* no call status? */
        ci->u.c.status = LUA_YIELD;  /* 'default' status */
    lua_assert(ci->u.c.status != LUA_OK);
    ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
    lua_unlock(L);
    n = (*ci->u.c.k)(L);
    lua_lock(L);
    api_checknelems(L, n);
    /* finish 'luaD_precall' */
    luaD_poscall(L, L->top - n);
}


static void unroll(lua_State *L, void *ud) {
    UNUSED(ud);
    for (;;) {
        if (L->ci == &L->base_ci)  /* stack is empty? */
            return;  /* coroutine finished normally */
        if (!isLua(L->ci))  /* C function? */
            finishCcall(L);
        else {  /* Lua function */
            luaV_finishOp(L);  /* finish interrupted instruction */
            luaV_execute(L);  /* execute down to higher C 'boundary' */
        }
    }
}


/*
** check whether thread has a suspended protected call
*/
static CallInfo *findpcall(lua_State *L) {
    CallInfo *ci;
    for (ci = L->ci; ci != NULL; ci = ci->previous) {  /* search for a pcall */
        if (ci->callstatus & CIST_YPCALL)
            return ci;
    }
    return NULL;  /* no pending pcall */
}


static int recover(lua_State *L, int status) {
    StkId oldtop;
    CallInfo *ci = findpcall(L);
    if (ci == NULL) return 0;  /* no recovery point */
    /* "finish" luaD_pcall */
    oldtop = restorestack(L, ci->extra);
    luaF_close(L, oldtop);
    seterrorobj(L, status, oldtop);
    L->ci = ci;
    L->allowhook = ci->u.c.old_allowhook;
    L->nny = 0;  /* should be zero to be yieldable */
    luaD_shrinkstack(L);
    L->errfunc = ci->u.c.old_errfunc;
    ci->callstatus |= CIST_STAT;  /* call has error status */
    ci->u.c.status = status;  /* (here it is) */
    return 1;  /* continue running the coroutine */
}


/*
** signal an error in the call to 'resume', not in the execution of the
** coroutine itself. (Such errors should not be handled by any coroutine
** error handler and should not kill the coroutine.)
*/
static l_noret resume_error(lua_State *L, const char *msg, StkId firstArg) {
    L->top = firstArg;  /* remove args from the stack */
    setsvalue2s(L, L->top, luaS_new(L, msg));  /* push error message */
    api_incr_top(L);
    luaD_throw(L, -1);  /* jump back to 'lua_resume' */
}


/*
** do the work for 'lua_resume' in protected mode
*/
static void resume(lua_State *L, void *ud) {
    int nCcalls = L->nCcalls;
    StkId firstArg = cast(StkId, ud);
    CallInfo *ci = L->ci;
    if (nCcalls >= LUAI_MAXCCALLS)
        resume_error(L, "C stack overflow", firstArg);
    if (L->status == LUA_OK) {  /* may be starting a coroutine */
        if (ci != &L->base_ci)  /* not in base level? */
            resume_error(L, "cannot resume non-suspended coroutine", firstArg);
        /* coroutine is in base level; start running it */
        if (!luaD_precall(L, firstArg - 1, LUA_MULTRET))  /* Lua function? */
            luaV_execute(L);  /* call it */
    } else if (L->status != LUA_YIELD)
        resume_error(L, "cannot resume dead coroutine", firstArg);
    else {  /* resuming from previous yield */
        L->status = LUA_OK;
        ci->func = restorestack(L, ci->extra);
        if (isLua(ci))  /* yielded inside a hook? */
            luaV_execute(L);  /* just continue running Lua code */
        else {  /* 'common' yield */
            if (ci->u.c.k != NULL) {  /* does it have a continuation? */
                int n;
                ci->u.c.status = LUA_YIELD;  /* 'default' status */
                ci->callstatus |= CIST_YIELDED;
                lua_unlock(L);
                n = (*ci->u.c.k)(L);  /* call continuation */
                lua_lock(L);
                api_checknelems(L, n);
                firstArg = L->top - n;  /* yield results come from continuation */
            }
            luaD_poscall(L, firstArg);  /* finish 'luaD_precall' */
        }
        unroll(L, NULL);
    }
    lua_assert(nCcalls == L->nCcalls);
}


LUA_API int lua_resume(lua_State *L, lua_State *from, int nargs) {
    int status;
    lua_lock(L);
    luai_userstateresume(L, nargs);
    L->nCcalls = (from) ? from->nCcalls + 1 : 1;
    L->nny = 0;  /* allow yields */
    api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
    status = luaD_rawrunprotected(L, resume, L->top - nargs);
    if (status == -1)  /* error calling 'lua_resume'? */
        status = LUA_ERRRUN;
    else {  /* yield or regular error */
        while (status != LUA_OK && status != LUA_YIELD) {  /* error? */
            if (recover(L, status))  /* recover point? */
                status = luaD_rawrunprotected(L, unroll, NULL);  /* run continuation */
            else {  /* unrecoverable error */
                L->status = cast_byte(status);  /* mark thread as `dead' */
                seterrorobj(L, status, L->top);
                L->ci->top = L->top;
                break;
            }
        }
        lua_assert(status == L->status);
    }
    L->nny = 1;  /* do not allow yields */
    L->nCcalls--;
    lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
    lua_unlock(L);
    return status;
}


LUA_API int lua_yieldk(lua_State *L, int nresults, int ctx, lua_CFunction k) {
    CallInfo *ci = L->ci;
    luai_userstateyield(L, nresults);
    lua_lock(L);
    api_checknelems(L, nresults);
    if (L->nny > 0) {
        if (L != G(L)->mainthread)
            luaG_runerror(L, "attempt to yield across a C-call boundary");
        else
            luaG_runerror(L, "attempt to yield from outside a coroutine");
    }
    L->status = LUA_YIELD;
    ci->extra = savestack(L, ci->func);  /* save current 'func' */
    if (isLua(ci)) {  /* inside a hook? */
        api_check(L, k == NULL, "hooks cannot continue after yielding");
    } else {
        if ((ci->u.c.k = k) != NULL)  /* is there a continuation? */
            ci->u.c.ctx = ctx;  /* save context */
        ci->func = L->top - nresults - 1;  /* protect stack below results */
        luaD_throw(L, LUA_YIELD);
    }
    lua_assert(ci->callstatus & CIST_HOOKED);  /* must be inside a hook */
    lua_unlock(L);
    return 0;  /* return to 'luaD_hook' */
}


int luaD_pcall(lua_State *L, Pfunc func, void *u,
               ptrdiff_t old_top, ptrdiff_t ef) {
    int status;
    CallInfo *old_ci = L->ci;
    lu_byte old_allowhooks = L->allowhook;
    unsigned short old_nny = L->nny;
    ptrdiff_t old_errfunc = L->errfunc;
    L->errfunc = ef;
    status = luaD_rawrunprotected(L, func, u);
    if (status != LUA_OK) {  /* an error occurred? */
        StkId oldtop = restorestack(L, old_top);
        luaF_close(L, oldtop);  /* close possible pending closures */
        seterrorobj(L, status, oldtop);
        L->ci = old_ci;
        L->allowhook = old_allowhooks;
        L->nny = old_nny;
        luaD_shrinkstack(L);
    }
    L->errfunc = old_errfunc;
    return status;
}



/*
** Execute a protected parser.
*/
struct SParser {  /* data to `f_parser' */
    ZIO *z;
    Mbuffer buff;  /* dynamic structure used by the scanner */
    Dyndata dyd;  /* dynamic structures used by the parser */
    const char *mode;
    const char *name;
};


static void checkmode(lua_State *L, const char *mode, const char *x) {
    if (mode && strchr(mode, x[0]) == NULL) {
        luaO_pushfstring(L,
                         "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
        luaD_throw(L, LUA_ERRSYNTAX);
    }
}


static void f_parser(lua_State *L, void *ud) {
    int i;
    Closure *cl;
    struct SParser *p = cast(struct SParser *, ud);
    int c = zgetc(p->z);  /* read first character */
    if (c == LUA_SIGNATURE[0]) {
        checkmode(L, p->mode, "binary");
        cl = luaU_undump(L, p->z, &p->buff, p->name);
    } else {
        checkmode(L, p->mode, "text");
        cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
    }
    lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
    for (i = 0; i < cl->l.nupvalues; i++) {  /* initialize upvalues */
        UpVal *up = luaF_newupval(L);
        cl->l.upvals[i] = up;
        luaC_objbarrier(L, cl, up);
    }
}


int luaD_protectedparser(lua_State *L, ZIO *z, const char *name,
                         const char *mode) {
    struct SParser p;
    int status;
    L->nny++;  /* cannot yield during parsing */
    p.z = z;
    p.name = name;
    p.mode = mode;
    p.dyd.actvar.arr = NULL;
    p.dyd.actvar.size = 0;
    p.dyd.gt.arr = NULL;
    p.dyd.gt.size = 0;
    p.dyd.label.arr = NULL;
    p.dyd.label.size = 0;
    luaZ_initbuffer(L, &p.buff);
    status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
    luaZ_freebuffer(L, &p.buff);
    luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
    luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
    luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
    L->nny--;
    return status;
}


